The project concerns comparing genetic organization of germinal and highly differentiated somatic nuclei for the same organism. In the coming year we will finish constructing single nullisomics for each of the five chromosomes. We shall continue to fill in the genetic map with the nullisomics, and to collect and map with homozygous deletion strains. All of these deficient germinal nuclei will be maintained in cells with normal somatic nuclei. Linkage of genes in the somatic nucleus will be detected by identifying instances of coassortment during vegetative growth. Somatically linked genes will be mapped in the germinal nucleus with the nullisomic and homozygous deletion strains. Meiotic segregation of diploid sets of chromosomes will be studied in strains with altered doses of the other chromosomes.